During blood loss due to hemorrhage, perfusing pressures can be kept near normal until the vol-ume loss overwhelms the system. Why is this so?

Question

a. Arteries constrict, increasing vascular re-sistance.
b. Arterioles dilate, decreasing vascular ca-pacity.
c. Muscle vessels dilate, increasing vascular capacity.
d. Venules constrict, decreasing vascular ca-pacity.

Answer 1

ANS: D
When blood loss occurs, as with hemorrhage, system capacity is decreased by constricting the venous vessels. Thus, perfusing pressures can be kept near normal until the volume loss over-whelms the system.